functional evaluation of occupational lung diseases

Functional evaluation of occupational lung diseases

Prof. Dr. Arif ÇımrınDokuz Eylül Univ Medical SchoolPulmonary Dept. İZMİR

acimrin@deu.edu.tr

Occupational lung diseases

Acute / subacute disordersAirway diseases

Asthma - RADS, Asthma-like syndrome- Byssinosis

Inhalational injury Toxic pneumonitis

Hypersensitivity pneumonitis

Chronic disorders

Interstititial fibrotic disorders Pneumoconiosis

Chronic bronchitis, COPD

MalignancyLung cancer, mesotelioma

Tools for functional evaluation of respiratory system

Spirometry Peak expiratory flow rate Flow-volume curve Lung volumes and DLco Nonspecific bronchial challenge Specific inhalation challenge Cardio-pulmonary exercise test

Indications of evaluation of pulmonary function at the workplace

Work fitness(?) Dangerous exposure risk,

Physical stress, respirator use

Spirometry

Exercise test

Surveillance and screening

Dangerous exposure (allergen, silica, asbestos)

Spirometry NSBHR

Diagnosis and Management

Obstructive defectRestrictive defect

Spirometry NSBHR

Lung volumes

DLco

Evaluation of Impairment and Disability

Medico-legal evaluation Spirometry DLco

Exercise test

Research Pulmonary effects of working conditions,Evaluation of new asthmagenic agent

Spirometry

SIC

Sood A., Pulmonary function tests at work. Clin Chest Med. 2001 Dec;22(4):783-93.

Spirometry

Key diagnostic element

- Not specific for causative diagnosis

- Not patognomonic for disease

Spirometry Indications in Occupational Health Primary prevention

Pe-employment evaluationJobs contain physical stressRespirator use

Screening of exposed workers about pulmonary problems Secondary prevention

Surveillance programsFrequency not clearEvaluation standarts not clearLower sensitivity for diagnosis of asthma and early interstitial lung disease

Tertiary preventionClinical evaluation of symptomatic cases

Obstructive – FEV1/FVC ↓ (FVC= N)Restrictive – FVC ↓ (FEV1/FVC= ↑ / N)

Grading of functional lossSeverity of pulmonary functional defect (impairment)Disability evaluation

Townsend, MC., et al. Spirometry in the Occupational Setting. JOEM 2000; 42(3), 228-245 Sood A., Pulmonary function tests at work. Clin Chest Med. 2001 Dec;22(4):783-93.Burge PS, et al. Peak flow records in the diagnosis of occupational asthma due to isocyanates. Thorax 1979; 34: 317-23

SpirometryNecessities

FEV1, FVC, FEV1/FVC, flow-volume curve Accuracy, standardization,

Equipment, technician, patient

? Normative values, race effect? Criteria for longitudinal follow up evaluation and acute

effect

Flow-volume relationshipIndications

Variable/fixed airway obstruction Vocal kord disfunction , FEF50 / FIF50 >1

Diagnosis and management of occupational asthmaLong term PEF measurement

Burge P. Thorax. 1979; 34: 308-16Chan-Yeung M. Chest. 1995; 108: 1084-1117

Diagnosis of occupational asthmaPEF vs FEV1

20 consecutive cases (occup asthma suspected) (+) SIC: 11 cases Un-inspected PEF and FEV1 record 3 readers

Sensitivity Specifity

PEF 73-82 89-100

FEV1 45-55 56-100

Leroyer C. Am J Respir Crit Care Med. 1998; 158: 827-832

Diagnosis Specific periods in a working

week(impairment/improvement)

Work-related asthma ≥3/4 working week Not work-related asthma 4/4 week Bipolar record %25-75/week

Insufficient record: Shortness of holiday periodsFrequent treatment changesContradictory data No exposure during record

Burge SP. Peak flow rate records in the diagnosis of occupational asthma due to colophony Thorax. 1979; 34: 308-16

PEF follow upVisual evaluation

PEF follow upVisual evaluation

Occupational asthma>%20 daily variationThis type of variation is more frequent during working days

OtherVariation only one time or irregular during days

Diagnostic value Sensitivity %93, Specifity %90

-Diurnal variation: Max-Min/Max x100

Liss GM. Peak expiratory flow rates in possible occupational asthma. Chest 1991; 100: 63-9

PEF follow upQuantitative evaluation

PEF follow upImportant points

n: 17 PEF follow up 6 times/day, 2wk work, >10days holiday, manuel and automatic record

Result; Lack of data % 22.0Reliable data % 55.3Insufficient record % 23.3

Conclusion: Training and motivation are important

Quirce S. Am J Respir Crit Care Med 1995; 152: 1100-2

Difference of consecutive measurements <20L/dmin Frequency of measurements= 2 hrs/day (4 measure/day)

Same measurement times Same equipment

Follow up period >2wk work , >2 weekend Start work after minimum 1 week off work period

No change in treatment No change for working conditions

Burge PS. Thorax. 1979; 34: 308-16Gannon PFG, Burge PS. Eur Respir J. 1997; 10(suppl 24): 57sSood A. Clin Chest Med. 2001 Dec;22(4):783-93

PEF follow upImportant points

PEF record evaluation;7 readerssoftware (OASYS-2)

Result;- Good agreement between readers - High variation between readers to establish asthma cases (low kappa

levels).- Poor agreement between readers about comment and OASYS-2 results

ConclusionAs a diagnostic tool, validity of OASYS-2 has to be confirm

Baldwin DR, et al. Interpretation of occupational peak flow records: level of agreement between expert clinicians and Oasys-2. Thorax 2002, 57:860–864

PEF follow upObjective, standard evaluation

Static lung volumes and DLcoIndications

Definite diagnosis of restrictive functional defect

- Total lung capacity , pneumoconiosis

Screening and early diagnosis

- DLco, beryliosis

Impairment and disability evaluation Evaluation of exposure – effect relationship

Sood A. Clin Chest Med. Pulmonary function tests at work. 2001;22(4):783-93

Nonspecific bronchial hyperreactivity

Metacholine Sensitivity ↑ = superficial inspiration Specificity ↑ = deep inspiration

Cut off level; PC20 8-16mg/ml sensitivity high, specificity medium NPV high, PPV medium COPD, allergic rhinitis, smoking

ATS. Guidelines for metacholine and exercise challenge testing. Am J Respir Crit Care Med. 2000; 161: 309-329

Diagnosis of occupational asthma- Evaluation of NSBHR in exposed, symptomatic,

spirometry normal cases- Characterization of natural history - Evaluation of response to intervention- Evaluation of changing in NSBHR before and after SIC

Nonspecific bronchial hyperreactivity Indications

Campo P. Advances in methods used in evaluation of occupational asthma. Curr Opin Pulm Med. 2004; 10:142–146 Sood A. Clin Chest Med. Pulmonary function tests at work. 2001;22(4):783-93Sastre J, et al.: Need for monitoring nonspecific bronchial hyperresponsiveness before and after isocyanate inhalation challenge. Chest 2003, 123:1276–1279

Nonspecific bronchial hyperreactivity Indications

Evaluation of asthma severity

Chan-Yeung M. Evluation of impairment/disability in patients with occupational asthma. Am Rev Respir Dis. 1987; 135: 950-51ATS. Guidelines for the evaluation of impairment/disability in patients with asthma. Am J Respir Crit Care Med. 1993; 147: 1056-61

Asthma severity

n PC20

mg/ml

FEV1

% pred.

0

1

2

3

4

42

16

12

11

6

11.6 ± 13.5

4.9 ± 9.0

1.4 ± 2.1

1.2 ± 2.0

0.4 ± 0.5

100 ± 15

93 ± 23

86 ± 27

86 ± 20

70 ± 21

Nonspecific bronchial hyperreactivity Important points

OA has no NSBHR ≥2 working-week enough for NSBHR test After 2 week working, (-) NSBHR rule out OA

- Maybe SIC (+)

Longer off work period, less NSBHR

NSBHR follow up; -PEF follow up = higher specifity and sensitivity

*Mapp CE., et al. TDI-induced asthma without airwayhyperresponsiveness. Eur Respir J. 1986; 68: 89-95#Vandenplas O. Increase in NSBHR as an early marker of bronchial response to occupational agents during specific inhalation challenges. Thorax 1996; 51: 472-478$Baur X, Relation between occupational asthma case history, bronchial metcholine challenge and specific challenge test in patients with suspected occupational asthma. Am J İndust Med 1998; 33: 114-122 Sood A. Clin Chest Med. Pulmonary function tests at work. 2001;22(4):783-93

Specific inhalation challengeIndications

Evaluation of airway response to responsible agent

-GOLD STANDARD-

After prevention of exposure at the workplace; Specific hyperreeactivity to allergen can continue NSBHR can be normalized

Lemiere C.Persistent specific bronchial reactivity to occupational agents in workers with normal nonspecific bronchial reactivity. Am J Respir Crit Care Med. 2000 Sep;162(3 Pt 1):976-80

Specific inhalation challengeIndications

Diagnosis of Occupational Asthma To define a new agent To evaluate a responsible agent in a complicated working

environment Definitive diagnosis, if there is a nontypical history or no

objective evidence about relation with the job

Diagnosis of Hypersensitivity Pneumonitis

Specific inhalation challenge limitations

Difficult to realize Time consumer Expensive Dangerous Trained staff, physician observer False negative and positive results often Difficult to differentiate acute reactions from irritant effect

Perfetti L. OA with sensitization to diphenylmethane diisocyanate (MDI) presenting at the onset like a RADS. Am J Ind Med 2003; 44:325–328Campo P. Advances in methods used in evaluation of occupational asthma. Curr Opin Pulm Med. 2004; 10:142–146

Specific inhalation challenge Important points

MDI exposed, symptomatic patient. After diagnosis of RADS, he went back to job Work related asthma revealed SIC test to MDI (+) Definite diagnosis : Occupational asthma

Conclusion; History and NSBHR results are not reliable

for OA diagnosis

Perfetti L. OA with sensitization to diphenylmethane diisocyanate (MDI) presenting at the onset like a RADS. Am J Ind Med 2003; 44:325–328

Cardio-pulmonary exercise test

Exercise induced asthma Evaluation of comorbidities with dyspnea Disability- impairment evaluation Pre-employment evaluations

Surveillance

Effect of occupational exposure on pulmonary functions

Acute effects of exposure-Pre-employment evaluation-Daily variations

Conclusion; Comparing with basal value Longitudinal change

Response to SABA Response to provocative agent

Effect of occupational exposure on pulmonary functions

Chronic effect of exposure-Pre-employment-Periodical evaluation

-difference between case and controls

Medicolegal conditions

-Impairment -Disability

Evaluation of impairment have to be multifactorial

ATS, exercise capacity graded with FEV1, FVC ve DLco ≤ %80, %FEV1 ≤%75 pred.

Disability criteria equal each parameterATS, Evalıuation of impairment/disability secondary to respiratory disorders. Am Rev Respir Dis. 1986; 133: 1205-09

n: 157 ♂, occupational related respiratory disorders suspected ECG normal, VO2max (≤2SD, mean FEV1) Comment;

- “FEV1, FVC, DLco, %FEV1 pred.” levels do not estimate disability- Submaximal exercise test results increase accuracy

Cotes JE, Lung function impairment as a guide to exercise limitation in work-related lung disorders. Am Rev Respir Dis 1988; 137: 1089-93

Permanent impairment grading

Parameter

Group 1 Group 2 Group 3 Group 4

İmpairment level (%)

0-9 10-25 26-50 51-100

FVC (%pred)

FEV1 (%pred)

DLco (%pred)

VO2max(ml/kg/min)

≥ below normal

“ “ “ “ “

“ “ “ “ “

≥25

60-79

“ “

“ “

≥20 and <25

51-59

“ “

“ “

≥15 and <20

≤ %50

≤ %40

≤ %40

<15

FVC, FEV1, DLco, Vo2max= %pred

AMA. Guide to the evaluation of permenent impairment. 2000

Examples of clinical applications

Occupational asthma

Diagnostic approach

History Immunolojik tests

In vivo test s(Skin prick test) In vitro tests

NSBHR Airway inflammation

Induced sputum Ekshaled NO

PEF follow up SIC at the workplace SIC at the lab

Mapp CE, et al. Occupational asthma. Am J Respir Crit Care Med. 2005; 172: 280-305Campo P. Advances in methods used in evaluation of occupational asthma. Curr Opin Pulm Med. 2004; 10:142–146

Diagnostic critera of OASurveillance Case Definition

(A) Diagnosis of asthma;(B) onset of asthma after entering the workplace; (C) association between symptoms of asthma and work; (D) one or more of the following criteria: (1) workplace exposure to an agent known to give rise to occupational asthma; (2) work-related changes in FEVi or PEF rate; (3) work-related changes in bronchial responsiveness; (4) positive response to specific inhalation challenge tests; (5) onset of asthma with a clear association with a symptomatic exposure to an irritant agent

in the workplace

Medical Case DefinitionOccupational asthma : A+B+C+D2 or D3 or D4 or D5 Likely Occupational asthma: A+B+C+ DI Work-aggravated asthma : A+C+ symptoms with exposure or medication need

Chan-Yeung M. Assessment of asthma in the workplace. Chest 1995;108;1084-1117

Diagnostic approach in OA

Chan-Yeung M. Assessment of asthma in the workplace. Chest 1995;108;1084-1117

Functional evaluation of pneumoconiosis

IPF, functional changes Pulmonary function tests

Restrictive= VC, TLC ve RV ↓ İsovolüme flow rates protected DLCO ↓ ABGs= normal or hipoksemia and respiratory alcalosis

Airway mechanics FEV1 and FVC ↓, FEV1/FVC protected Elastic recoil ↑, Airflow / lung volume ↑

Gas exchange during resting and exercise A-aPO2 with exercise ↑ (%20-30), PaO2 ve SaO2 ↓

Pulmonary hemodynamics Early, resting Pulmonary hypertension not common VC <%50 pred or DLco %45 pred (Pulm. HT usual)

ATS guidelines: Idiopathic pulmonary fibrosis: Diagnosis and treatment Am J Respir Crit Care Med 2000; 161:646.

Silica exposure and functional effects

Silica exposure with not silicosis; Chronic obstructive defect Hypersecretion Pathology; emphysema

Moderate to severe silicosis; Small and medium size airways narrowing and distortion Large airways; BALT hypertrophia

Very severe silicosis; İrreversible obstructive defect + interstital lung disease

The official statement of the ATS. ATS guidelines: Adverse effects of crystalline silica exposure. Am J Respir Crit Care Med 1997; 155:761.

Research

Silicosis, correlation between HRCT findings and functional variations

n: 41, stone carver, HRCT and functional evaluation

Decreasing in lung volumes related to severity of silicosis

dos Santos Antao VC, et al. High-Resolution CT in Silicosis. Correlation With Radiographic Findings and Functional Impairment. J Comput Assist Tomogr 2005;29:350–356

Surveillance

Surveillance for prevention of silicosis Inclusion criteria= high level silica exposed person

(≥0.05 mg/m3 crystalline silica) Evaluation items

1. History (Occupational and medical) 2. Physical examination 3. Tuberculin test 4. Chest X-ray 5. Spirometry

Calendar 1. Pre-employment 2. Follow-up (<12 ay)

- <0.05mg/m3 dust exposed, <10 yrs working, 1 time/3 yrs,- >10 yrs working, 1 time/2 yrs - High level exposure, close observation

3. Leaving work evaluation Managing with experienced physician

Raymond LW, Wintermeyer S. Medical Surveillance of Workers Exposed to Crystalline Silica. JOEM. 2006; 48(1): 95-101

Surveillance for Occupational Asthma

Lower level: - Probabl respiratory threat

- If there are preventive measures:

A)Pre-employment evaluation + FEV1 ve FVC

B)Inform workers(exposure and symptoms)

C)Report symptoms to manager

D)Annual questionnaire

High level:- Strong respiratory thread A) Pre-employment evaluation + FEV1

ve FVC

B) Inform workers(exposure and symptoms)

C) Report symptoms to manager

D)Questionnaire (6 and 12. wk)

E) Annual questionnaire

F) Spirometry

G)Immunological tests

Fishwick D., Standards of care for occupational asthma. Thorax 2008;63;240-250

Surveillance, Diisocyanate workplaces 1983, Ontario,Canada, Diisocyanate measurement in working areas;

<5 ppb / mean 8h ve 20 ppb / short term exposure

Surveillance programme-Pre-employment evaluation respiratory questionnaire + spirometry- Respiratory questionnaire (6. month at work)-Annual spirometry-Workers who have respiratory symptoms and spirometric variations goes next step

Tarlo SM, Liss GM. Diisocyanate-Induced Asthma: Diagnosis, Prognosis, and Effects of Medical Surveillance Measures. Appl Occup Envir l Hyg. 2002; 17(12): 902–908

Effect of surveillance on OA

Tarlo SM, Liss GM. Diisocyanate-Induced Asthma: Diagnosis, Prognosis, and Effects of Medical Surveillance Measures. Appl Occup Envir l Hyg. 2002; 17(12): 902–908

-Early diagnosis-Better prevention of pulmonary functions-Better prognosis

Tarlo SM, Liss GM. Diisocyanate-Induced Asthma: Diagnosis, Prognosis, and Effects of Medical Surveillance Measures. Appl Occup Envir l Hyg. 2002; 17(12): 902–908

Effect of surveillance on OAResults

Conclusion

Functional evaluation is a key element of occupational lung disorders

Aim of the evaluation determine method

Thank you

acimrin@deu.edu.tr